3 phase cable CCC

[Glospark]

When selecting cable size for a new circuit, how close do you let the cables CCC get to the rating of the fuse protecting it before moving up to the next CSA?

 

[NozSpark]

Current carrying capacity is only the first thing to look at when selecting a cable

Volt drop and calculated Zs have more of a bearing on cable selection than the current carrying capacity IMHO

 

[Glospark]

Yes it does. All calcs have been done and all satisfy the regs. So was wondering when you end up with your cable CCC within a few amps of the OCPD do you stay with it as it complie of select the next size up

 

[Sidewinder]

Depends on how big, have you based it on 90 deg cable with 70 deg accessories, in which case you will need to go up a size.

If the cable is big, over its operating lifetime it may be cheaper to put in a larger cable thus reducing the Joule heating losses.

 

[NozSpark]

I would tend to go with how close it is to the volt drop limit rather than how close it is to the CCC

If it passes CCC then thats enough for me

 

[kme]

I tend to very my decision, based on a lot of different criteria:

duty cycle; EXACT load characteristics compared to cable, how close to max. limits it is, on ccc; vd and max Zs

Sorry - not definitive, but I don`t feel there is a "one size fits all" type answer, I`m afraid

KME